Transmitting and receiving appliances (transmitters and receivers) are used in message systems having a message transmission path between a message source and a message sink for message processing and transmission, for those appliances in which
1) the message processing and message transmission can take place in a preferred transmission direction (simplex operation) or in both transmission directions (duplex operation);
2) the message processing is analog or digital; or
3) the message transmission via the long-distance transmission path is wire-based or is carried out without wires (for example by radio transmission) on the basis of various message transmission methods FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access) and/or CDMA (Code Division Multiple Access)xe2x80x94for example in accordance with radio standards such as DECT, GSM, WACS or PACS, IS-54, IS-95, PHS, PDC etc. [see IEEE Communications Magazine, January 1995, pages 50 to 57; D. D. Falconer et al.: xe2x80x9cTime Division Multiple Access Methods for Wireless Personal Communicationsxe2x80x9d].
xe2x80x9cMessagexe2x80x9d is a generic term that covers both the content (information) and the physical representation (signal). Despite a message having the same contentxe2x80x94(i.e., the same information different signal forms may occur. Thus, for example, a message relating to one item may be transmitted
(1) in the form of a picture;
(2) as the spoken word;
(3) as the written word;
(4) as an encrypted word or picture.
The transmission types in situation (1) to (3) are, in this case, normally characterized by continuous (analog) signals, while the transmission type in (4) normally consists of discontinuous signals (for example pulses, digital signals).
Based on this general definition of a message system, the invention relates to a method for assessing transmission channels in telecommunications systems using wire-free telecommunication, as claimed in the precharacterizing clauses of patent claims 1, 6, 9 and 11, and to transceiver for assessing transmission channels in telecommunications systems using wireless telecommunication, as claimed in the precharacterizing clauses of patent claims 22, 27, 30 and 32.
Telecommunications systems using wireless telecommunication, as are presented and described in the following documents (1): Nachrichtentechnik Elektronik [Electronic information technology], Berlin 45, 1995, Issue 1, pages 10 to 14 and Issue 2, pages 24 to 27; P. Jung, B. Steiner: xe2x80x9cKonzept eines CDMA-Mobilfunksystems mit gemeinsamer Detektion fxc3xcr die dritte Mobilfunkgenerationxe2x80x9d [Concept of a CDMA mobile radio system with joint detection for the third mobile radio generation]; (2): Nachrichtentechnik Elektronik [Electronic information technology], Berlin 41, 1991, Issue 6, pages 223 to 227 and page 234; P. W. Baier, P. Jung, A. Klein: xe2x80x9cCDMAxe2x80x94ein gxc3xcnstiges Vielfachzugriffsverfahren fxc3xcr frequenzselektive and zeitvariante Mobilfunkkanxc3xa4lexe2x80x9d [CDMAxe2x80x94a useful multiple-access method for frequency-selective and time-variant mobile radio channels]; (3): IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E79-A, No. 12, December 1996, pages 1930 to 1937; P. W. Baier, P. Jung: xe2x80x9cCDMA Myths and Realities Revisitedxe2x80x9d; (4): IEEE Personal Communications, February 1995, pages 38 to 47; A. Urie, M. Streeton, C. Mourot: xe2x80x9cAn Advanced TDMA Mobile Access System for UMTSxe2x80x9d; (5): telekom praxis, May 1995, pages 9 to 14; P. W. Baier: xe2x80x9cSpread-Spectrum-Technik and CDMAxe2x80x94eine ursprxc3xcnglich militxc3xa4rische Technik erobert den zivilen Bereichxe2x80x9d [Spread spectrum technology and CMDAxe2x80x94an originally military technology takes over the civil area]; (6): IEEE Personal Communications, February 1995, pages 48 to 53; P. G. Andermo, L. M. Ewerbring: xe2x80x9cA CDMA-Based Radio Access Design for UMTSxe2x80x9d; (7): ITG Fachberichte [ITG Specialist Reports] 124 (1993), Berlin, Offenbach: VDE Verlag ISBN 3-8007-1965-7, pages 67 to 75; Dr. T. Zimmermann, Siemens A G: xe2x80x9cAnwendung von CDMA in der Mobilkommunikationxe2x80x9d [Use of CDMA for mobile communication]; (8): telecom report 16, (1993), Issue 1, pages 38 to 41; Dr. T. Ketseoglou, Siemens A G and Dr. T. Zimmermann, Siemens A G: xe2x80x9cEffizienter Teilnehmerzugriff fxc3xcr die 3. Generation der Mobilkommunikationxe2x80x94Vielfachzugriffsverfahren CDMA macht Luftschnittstelle flexiblerxe2x80x9d [Efficient subscriber access for 3rd generation mobile communicationxe2x80x94multiple-access methods CDMA makes the radio interface more flexible], are referred to as the future third-generation radio telecommunications scenario, based on the prospect of a Universal Mobile Telecommunications System (UMTS).
The second generation radio telecommunications scenario is currently governed, in the microcell and macrocell area, by the GSM-specific radio telecommunications system based on the FDMA/TDMA/FDD transmission principle (Frequency Division Duplex) [Global System for Mobile Communication; vgl. (1): Informatik Spectrum [Information technology spectrum] 14, (1991) June, No. 3, Berlin, DE; A. Mann: xe2x80x9cDer GSM-Standardxe2x80x94Grundlage fxc3xcr digitale europxc3xa4ische Mobilfunknetzexe2x80x9d [The GSM Standardxe2x80x94the basis for digital European mobile radio networks], pages 137 to 152; (2): R. Steele: Mobile Radio Communications, Pentech Press, 1992 (Reprint 1994), Chapter 8: The Pan-European Digital Cellular Mobile Radio Systemxe2x80x94known as GSM, pages 677 ff.; (3): telekom praxis April 1993, P. Smolka: xe2x80x9cGSM-Funkschnittstellexe2x80x94Elemente und Funktionenxe2x80x9d [GSM radio interfacexe2x80x94elements and functions], pages 17 and 24] and, in the picocell area, by the DECT telecommunications system based on the FDMA/TDMA/TDD transmission principle (Time Division Duplex) [Digital Enhanced (previously: European) Cordless Telecommunication; see (1): Nachrichtentechnik Elektronik [Electronics information technology] 42 (1992) January/February No. 1, Berlin, DE; U. Pilger xe2x80x9cStruktur des DECT-Standardsxe2x80x9d [Structure of the DECT Standard], pages 23 to 29 in conjunction with ETSI Publication ETS 300175-1 . . . 9, October 1992; (2); telecom report 16 (1993), No. 1, J. H. Koch: xe2x80x9cDigitaler Komfort fxc3xcr schnurlose Telekommunikationxe2x80x94DECT-Standard erxc3x6ffnet neue Nutzungsgebietexe2x80x9d [Digital convenience for cordless communicationsxe2x80x94the DECT Standard opens up new fields of use], pages 26 and 27; (3): tec 2/93xe2x80x94The technical magazine from Ascom xe2x80x9cWege zur universellen mobilen Telekommunikationxe2x80x9d [Approaches to universal mobile telecommunications], pages 35 to 42; (4): Philips Telecommunication Review Vol. 49, No. 3, September 1991, R. J. Mulder: xe2x80x9cDECT, a universal cordless access systemxe2x80x9d; (5): WO 93/21719 (FIGS. 1 to 3 with associated description)].
FIG. 1 shows the TCH multiframe, TDMA frame and TDMA timeslot structure for the GSM mobile radio concept which is known for user data transmission on the traffic channel (Traffic Channel TCH) from the documents xe2x80x9c(1): Informatik Spectrum [Information technology spectrum] 14 (1991) June, No. 3, Berlin, DE; A. Mann: xe2x80x9cDer GSM-Standardxe2x80x94Grundlage fxc3xcr digitale europxc3xa4ische Mobilfunknetzexe2x80x9d [The GSM Standardxe2x80x94The basis for digital European modile radio networks], pages 137 to 152; (2): R. Steele: Mobile Radio Communications, Pentech Press, 1992 (Reprint 1994), Chapter 8: The Pan-European Digital Cellular Mobile Radio Systemxe2x80x94known as GSM, pages 677 ff.; (3): telekom praxis April 1993, P. Smolka: xe2x80x9cGSM-Funkschnittstellexe2x80x94Elemente und Funktionenxe2x80x9d [GSM radio interfacexe2x80x94elements and functions], pages 17 and 24xe2x80x9d, in which the data embedded in the described structure are transmitted using the FDD principle in the uplink path or uplink direction (uplink; xe2x80x9cmobile stationxe2x86x92base stationxe2x80x9d transmission) in the frequency band between 890 MHz and 915 MHz and in the downlink path or downlink direction (downlink; xe2x80x9cbase stationxe2x86x92mobile stationxe2x80x9d transmission) in the frequency band between 935 MHz and 960 MHz.
FIG. 2 shows the multiframe, TDMA frame and TDMA timeslot structure of the DECT mobile radio concept which is known from the document xe2x80x9cNachrichtentechnik Elektronik [Electronics information technology] 42 (1992) January/February, No. 1, Berlin, DE; U. Pilger xe2x80x9cStruktur des DECT-Standardsxe2x80x9d [Structure of the DECT Standard], pages 23 to 29xe2x80x9d, in which the data embedded in the described structure are transmitted, using the TDD principle, in the timeslots 0 . . . 11 in the downlink path or downlink direction (downlink; xe2x80x9cbase stationxe2x86x92mobile stationxe2x80x9d transmission), and in the timeslots 12 . . . 23 in the uplink path or uplink direction (uplink; xe2x80x9cmobile stationxe2x86x92base stationxe2x80x9d transmission).
Based on the document Nachrichtentechnik Elektronik [Electronics information technology], Berlin 45, 1995, Issue 1, pages 10 to 14 and Issue 2, pages 24 to 27; P. Jung, B. Steiner: xe2x80x9cKonzept eines CDMA-Mobilfunksystems mit gemeinsamer Detektion fxc3xcr die dritte Mobilfunkgenerationxe2x80x9d [Concept of a third mobile radio generation CDMA mobile radio system with joint detection], FIG. 3 shows a possible FDMA/TDMA/CDMA multiple access for the uplink path (uplink; xe2x80x9cmobile stationxe2x86x92base stationxe2x80x9d transmission direction) and downlink path (uplink; xe2x80x9cbase stationxe2x86x92mobile stationxe2x80x9d transmission direction) of a telecommunications system with CDMA, FDMA and TDMA multiple-access components, for example a Joint Detection CMDA mobile ratio concept, in whichxe2x80x94as in the GSM system (see FIG. 1)xe2x80x94the data are transmitted using the FDD principle in the uplink path or uplink direction (uplink; xe2x80x9cmobile stationxe2x86x92base stationxe2x80x9d transmission) and in the downlink path or downlink direction (downlink; xe2x80x9cbase stationxe2x86x92mobile stationxe2x80x9d transmission) in different frequency bands.
The number of simultaneously active subscribersk in one timeslot is, for example, K=8.
Based on the illustration of multiple access in FIG. 3, FIG. 4 shows the timeslot structure (burst structure) for the uplink path (uplink; xe2x80x9cmobile partxe2x86x92base stationxe2x80x9d transmission direction) for the Joint Detection CDMA mobile radio concept, which is known from the document Nachrichtentechnik Elektronik [Electronics information technology], Berlin 45, 1995, Issue 1, pages 10 to 14 and Issue 2, pages 24 to 27; P. Jung, B. Steiner: xe2x80x9cKonzept eines CMDA-Mobilfunk-systems mit gemeinsamer Detektion fxc3xcr die dritte Mobilfunkgenerationxe2x80x9d [Concept of a third-generation CDMA mobile radio system with joint detection] and is illustrated, in particular, in FIG. 5 of that document.
The 24 user data block data symbols shown in FIG. 4 are spread using a subscriber-specific spread code with a spreading factor of Q=14, so that each data symbol 14 contains data elements in the form of xe2x80x9cchipsxe2x80x9d. Based on a GSM radio scenario with, for example, two radio cells and base stations (Base Transceiver Station) arranged in them, in which case a first base station BTS1 (transmitter/receiver; transceiver) xe2x80x9cilluminatesxe2x80x9d a first radio cell FZ1 and a second base station BTS2 (transmitter/receiver; transceiver) xe2x80x9cilluminatesxe2x80x9d a second radio cell FZ2, omnidirectionally, FIG. 5 shows an FDMA/TDMA/CDMA radio scenario in which the base stations BTS1, BTS2 are connected or can be connected via a radio interface, which is designed for the FDMA/TDMA/CDMA radio scenario, to a number of mobile stations MS1 . . . MS5 (transmitters/receivers; transceiver) located in the radio cells FZ1, FZ2, via wire-free unidirectional or bidirectionalxe2x80x94uplink direction UL and/or downlink direction DLxe2x80x94telecommunication on appropriate transmission channels TRC. The base stations BTS1, BTS2 are connected in a known manner (see the GSM telecommunications system) to a base station controller BSC (Base Station Controller), which carries out the frequency management and switching functions while controlling the base stations. For its part, the base station controller BSC is connected via a mobile switching center MSC (Mobile Switching Center) to the higher-level telecommunications network, for example to the PSTN (Public Switched Telecommunications Network). The mobile switching center MSC is the management center for the illustrated telecommunications system. It carries out all the call management and, using associated registers (not illustrated), the authentication of the telecommunications subscribers as well as position monitoring in the network.
FIG. 6 shows the fundamental layout of the base station BTS1, BTS2, which is in the form of a transmitter/receiver response transceiver, while FIG. 7 shows the fundamental layout of the mobile station MT1 . . . MT5, which is likewise in the form of a transmitter/receiver response transceiver. The base station BTS1, BTS2 carries out the transmission and reception of radio messages from and to the mobile station MTS1 . . . MTS5, while the mobile station MT1 . . . MT5 carries out the transmission and reception of radio messages from and to the base station BTS1, BTS2. For this purpose, the base station has a transmitting antenna SAN and a receiving antenna EAN, while the mobile station MT1 . . . MT5 has one antenna ANT, which can be controlled by an antenna switch AU and is used jointly for transmission and reception. In the up-link direction (reception path), the base station BTS1, BTS2 receives, for example, via the receiving antenna EAN at least one radio message FN with an FDMA/TDMA/CDMA component from at least one of the mobile stations MT1 . . . MT5, while, in the downlink direction (reception path), the mobile station MT1 . . . MT5 receives, for example, at least one radio message FN with an FDMA/TDMA/CDMA component from at least one base station BTS1, BTS2, via the joint antenna ANT. The radio message FN in this case comprises, a broadband-spread carrier signal with modulated information composed of data symbols.
The received carrier signal is filtered and mixed down to an intermediate frequency in a radio receiving device FEE, and this intermediate frequency is, for its part, then sampled and quantized. After analog/digital conversion, the signal (which has been subject to distortion from multipath propagation on the radio path) is fed to an equalizer EQL, which compensates for the majority of the distortion keyword: synchronization).
A channel assessor KS then attempts to assess the transmission characteristics of the transmission channel TRC on which the radio message FN was transmitted. The transmission characteristics of the channel are in this case produced in the time domain by means of the channel impulse response. In order that the channel impulse response can be assessed, the radio message FN is assigned or allocated, at the transmission end (in the present case by the mobile station MS1 . . . MS5 or the base station BTS1, BTS2), specific additional information, which is constructed as a training information sequence and is in the form of a so-called midamble.
A joint data detector DD, which follows this and is used for all the received signals, is then used to remove the distortion from and to separate the individual mobile-station-specific signal elements contained in the common signal in a known manner. After distortion removal and separation, the data symbols, which were previously present, are converted into binary data in a symbol-to-data converter SDW After this, a demodulator DMOD is used to obtain the original bit stream from the intermediate frequency before, the individual timeslots are assigned to the correct logical channels in a demutiplex DMUX, and thus to the various mobile stations as well.
The received bit sequence is decoded channel-by-channel in a channel codec KC. Depending on the channel, the bit information is assigned to the control and signaling timeslot or to a voice timeslot and, in the case of the base station (FIG. 6), the control and signaling data and the voice data are jointly passed to an interface SS, which is responsible for signaling and voice coding/decoding (voice codec) for transmission to the base station controller BSC, while, in the case of the mobile station (FIG. 7), the control and signaling data are passed to a control and signaling unit STSE, which is responsible for all the signaling and control in the mobile station, and the voice data are passed to a voice codec SPC, which is designed for voice inputting and outputting.
The voice data are in a predetermined data stream (e.g., 64 kbit/s stream in the network direction or 13 kbit/s stream in the network direction) in the voice codec of the interface SS in the base station BTS1, BTS2.
All the control for the base station BTS1, BTS2 is carried out in a control unit STE.
In the downlink direction (transmission path), the base station BTS1, BTS2 sends, for example, at least one radio message FN with an FDMA/TDMA/CDMA component via the transmitting antenna SAN to at least one of the mobile stations MT1 . . . MT5 while, in the uplink direction (transmission path), the mobile station MS1 . . . MS5 sends, for example, at least one radio message FN with an FDMA/TDMA/CDMA component, via the common antenna ANT to at least one base station BTS1, BTS2.
The transmission path starts in the base station BTS1, BTS2 in FIG. 6 by control and signaling data received in the channel codec KC via the interface SS from the base station controller BSC, as well as voice data being assigned to a control and signaling timeslot or a voice timeslot, with these timeslots being coded channel-by-channel into a bit sequence.
The transmission path starts in the mobile station MS1 . . . MS5 in FIG. 7 by voice data (received in the channel codec KC from the voice codec SPC) and control and signaling data (received from the control and signaling unit STSE) being assigned to a control and signaling timeslot or a voice timeslot, and these timeslots are coded channel-by-channel into a bit sequence.
The bit sequence obtained in the base station BTS1, BTS2 and in the mobile station MS1 . . . MS5 is in each case converted into data symbols in a data-to-symbol converter DSW. Following this, the data symbols are in each case spread in a spreading device SPE using a respective subscriber-specific code. The burst generator BG comprises a burst former BZS and a multiplexer MUX, and, after the previous step, the burst former BZS is in each case used to add a training information sequence, in the form of a midamble for channel assessment, to the spread data symbols, and the burst information obtained in this way is in each case placed in the correct timeslot in the multiplexer MUX. Finally, the burst that has been obtained is in each case radio-frequency modulated and digital/analog converted in a modulator MOD, before the signal obtained in this way is transmitted as a radio message FN, via a radio transmitting device FSE, to the transmitting antenna SAN or to the common antenna ANT.
Telecommunications systems using wire-free telecommunication are subject, in the same way as, for example, the mobile radio system illustrated in FIG. 5, to the known problem (see: documents (1): Nachrichtentechnik Elektronik [Electronic information technology], Berlin 45, 1995, Issue 1, pages 10 to 14 and Issue 2, pages 24 to 27; P. Jung, B. Steiner: xe2x80x9cKonzept eines CMDA-Mobilfunksystems mit gemeinsamer Detektion fnr die dritte Mobilfunkgenerationxe2x80x9d [Concept of a third generation CDMA mobile radio system with joint detection]; (2): Nachrichtentechnik Elektronik [Electronic information technology], Berlin 41, 1991, Issue 6, pages 223 to 227 and page 234; P. W. Baier, P. Jung, A. Klein: xe2x80x9cCMDAxe2x80x94ein gxc3xcnstiges Vielfachzugriffsverfahren fxc3xcr frequenzselektive und zeitvariante Mobilfunkkanxc3xa4lexe2x80x9d [CMDAxe2x80x94a useful multiple-access method for frequency-selective and time-variant mobile radio channels]; (3): IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, Vol. E79-A, No. 12, December 1996, pages 1930 to 1937; P. W. Baier, P. Jung: xe2x80x9cCMDA Myths and Realities Revisitedxe2x80x9d; (4): IEEE Personal Communications, February 1995, pages 38 to 47; A. Urie, M. Streeton, C. Mourot: xe2x80x9cAn Advanced TDMA Mobile Access System for UMTSxe2x80x9d; (5): telekom praxis, May 1995, pages 9 to 14; P. W. Baier: xe2x80x9cSpread-Spectrum-Technik und CMDAxe2x80x94eine ursprxc3xcnglich militxc3xa4rische Technik erobert den zivilen Bereichxe2x80x9d [Spread spectrum technology and CDMAxe2x80x94an originally military technology takes over the civil area]; (6): IEEE Personal Communications, February 1995, pages 48 to 53; P. G. Andermo, L. M. Ewerbring: xe2x80x9cA CDMA-Based Radio Access Design for UMTSxe2x80x9d; (7): ITG Fachberichte [ITG Specialist Reports] 124 (1993), Berlin, Offenbach: VDE Verlag ISBN 3-8007-1965-7, pages 67 to 75; Dr. T. Zimmermann, Siemens A G: xe2x80x9cAnwendung von CDMA in der Mobilkommunikationxe2x80x9d [Use of CMDA for mobile communication]; (8): telecom report 16, (1993), Issue 1, pages 38 to 41; Dr. T. Ketseoglou, Siemens A G and Dr. T. Zimmermann, Siemens A G: xe2x80x9cEffizienter Teilnehmerzugriff fxc3xcr die 3. Generation der Mobilkommunikationxe2x80x94Vielfachzugriffsverfahren CMDA macht Luftschnittstelle flexiblerxe2x80x9d [Efficient subscriber access for 3rd generation mobile communicationsxe2x80x94CDMA multiple-access method makes the radio interface more flexible]), that the transmission characteristics of the transmission path, of the transmission channel and of the mobile radio channel vary with time. In the time domain, the transmission characteristics of the mobile radio channel are characterized by the channel impulse response. Particularly in TDMA-based mobile radio systems, attempts are therefore made in a known manner to assess the channel impulse response of the mobile radio channel. This is done by inserting training sequences or test signals, so-called midambles, in the respective message to be transmitted (i.e., the burst in the TDMA-based telecommunications systems). The channel impulse response of the mobile radio channel can then be determined using the received signal, which originates from the training sequence or the test signals.
The object on which the invention is based is to improve, to simplify and to optimize the assessment of wireless transmission channels in telecommunications systems.
This and other objects are achieved by an aspect of the present invention including the method for assessment of transmission channels in telecommunications systems using wire-free telecommunication. A first receiver receives a first message, the first message being transmitted by a first transmitter and at least one further message is received that is transmitted by the first transmitter or a further transmitter. The at least one further message is transmitted in a same direction of transmission as the first message. The transmission channel is then assessed based on the first message and the at least one further message.
According to a further aspect of the present invention, a method includes assigning messages to timeslots and assessing channel impulse responses for the timeslots in the messages. Included in the method is assessing a first channel impulse response and a second channel impulse response. A sufficient similarity is identified between the first channel impulse response and the second channel impulse response when a difference by which the first channel impulse response differs from the second channel impulse response is less than a predetermined limit value. A mean channel impulse response is then formed from the first channel impulse response and a second channel impulse response when the impulse responses are identified as being sufficiently similar.
According to yet another aspect of the present invention, a transmitter/receiver for assessing transmission channels is provided having a channel assessment device. The channel assessment device is configured such that when the transmitter/receiver receives a first message transmitted by an opposing station at least one further message which is transmitted by the opposing station or a further opposing station in the same transmission direction as the transmitter receiver allows the channel assessment device to assess the transmission channel based on the first message and the at least one further message.
Furthermore, based on the transceiver defined in the precharacterizing clause of patent claims 22, 27, 30 and 32, the object is achieved by the features specified in the characterizing part of patent claims 22, 27, 30 and 32.
The idea on which the invention is based is essentially to use correlations of different channel impulse responses. This can be achieved by
(i) a telecommunications subscriber [for example, according to FIG. 5, a system-internal subscriber at the mobile station MS1 . . . MS5 or another system-internal subscriber at the mobile station MS1 . . . MS5 (internal link) or a system-external subscriber in the higher-level PST network (external link)] receives the messages intended for him (in the case of TDMA-based telecommunications systems, a subscriber to whom, for example, the timeslot #n of a TDMA frame is assigned) and also uses messages which are intended for other subscribers that are transmitted in the same transmission direction (in the case of TDMA-based telecommunications systems, another subscriber to whom, for example, the timeslot #nxe2x88x921 in. This allows a considerable improvement to be achieved in the bit error rate (BER or link level performance), which is a function of the bit energy to noise power density [BER=f (Eb/NO)].
(ii) In addition, two sufficiently similar channel impulse responses in different (not necessarily successive) timeslots are assessed, and are averaged if their difference is less than a predetermined limit value. It is thus possible for a lower Eb/NO to be required for a given bit error rate BER than if this information were not used.
(iii) In addition, in the event of two sufficiently similar channel impulse responses whose difference is less than a predetermined limit value, no training information sequence or tests signals (midambles) is or are transmitted each n-th transmission timeslot, for (e.g., every other burst). This allows, in particular, the data rate of the respective subscriber to be increased.
(iv) In addition, LOOK-UP tables are produced for different telecommunications systems carrier frequencies, in which tables the relationship xe2x80x9ccorrelation coefficientxe2x80x9d speed of the subscriber with respect to the carrier frequency (absolute speed)xe2x80x9d is shown. The tables allow the channel assessment to be simplified. However, one precondition for producing the tables is that the correlation characteristics of assessed channel impulse responses have previously been investigated, and the relative speed of a subscriber is estimated as a function of this. Since the assessed channel impulse responses correlates, the subscriber is moving at a slow relative speed. If the assessed channel impulse responses do not correlate, the subscriber is moving at a high relative speed.
Additional advantages and novel features of the invention will be set forth, in part, in the description that follows and, in part, will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.